Search Results (1,113)

We present a morphokinematic analysis based on high-resolution long-slit echelle spectroscopy of the [N ii]$\lambda 6583$ line and narrowband imaging. Position–velocity diagrams reveal asymmetric expansion and localized kinematic features. We derive a systemic velocity of $V_{\mathrm{sys}}^{\mathrm{LSR}}=-25\pm 1$ km s⁻¹ ($V_{\mathrm{sys}}^{\mathrm{HEL}}=-34\pm 1$ km s⁻¹) and a main shell expansion velocity of $V_{\exp }=22\pm 1$ km s⁻¹. Three-dimensional modeling indicates an ellipsoidal main body surrounded by a thin shell, two ear-like protrusions, and additional small-scale structures. The corresponding kinematic ages are $3600\pm 700$ yr for the ellipsoid and ring, and $7500\pm 1000$ yr and $8800\pm 1500$ yr for the two opposite ear-like protrusions, respectively, indicating that these outer structures predate the main nebular envelope. The kinematic asymmetry and enhanced emission regions suggest evolution within a non-uniform ambient medium. At the same time, the presence of collimated ear-like structures is consistent with shaping influenced by binary interaction, where earlier outflows preceded the ejection of the dense shell. NGC 6563 therefore appears to be a dynamically evolved system shaped by the combined effects of episodic mass ejection and environmental interaction. Full article

Ambient-temperature asphalt binders have emerged as a sustainable alternative to traditional hot-mix asphalt, offering significant advantages in energy conservation and emission reduction. This review systematically examines the research progress and development trends of high-performance reactive asphalt binders designed for ambient-temperature application, which achieve enhanced performance through chemical cross-linking reactions. The study focuses on three core material systems: epoxy resin, waterborne epoxy emulsified asphalt, and polyurethane. For each system, we comprehensively summarize the material composition, strength formation mechanisms, and mix design methodologies. Key evaluation methods for critical pavement performance—including strength characteristics, water stability, and high-temperature performance—are critically reviewed. Furthermore, microscopic characterization techniques including scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FTIR), and differential scanning calorimetry (DSC) are discussed to elucidate the underlying mechanisms governing performance evolution. Analysis reveals that epoxy-based binders exhibit superior strength and stiffness, rendering them suitable for heavy-traffic pavements; waterborne epoxy emulsified asphalt binders combine environmental compatibility with construction convenience for thin-layer rehabilitation, while polyurethane-based binders demonstrate exceptional elasticity and rapid curing characteristics for quick-traffic-opening scenarios. Although current research has established a preliminary performance evaluation framework, the absence of unified technical standards constrains widespread engineering implementation. Future research priorities should focus on developing water-triggered curing systems, intelligent responsive materials, and comprehensive standardization systems to fully harness the engineering potential of these sustainable binders. Full article

The European Union (EU) and national governments have set clear targets to reduce agricultural emissions, including ammonia from manure spreading practice, with regulations such as the Ambient Air Quality (AQ) and Clean Air Directives, the Common Agricultural Policy (CAP), and the Green Deal, with implication for ecosystem services and landscape planning, reflecting broader environmental sustainability objectives including those addressed by the Sustainable Development Goals (SDGs). Informative Inventory Reports (IIRs) are critical tools within the EMEP/EEA framework for monitoring long-range transboundary air pollution. They utilize three distinct methodological tiers (Tiers 1, 2, and 3) to estimate emission data across Europe. Despite the availability of Earth Observation (EO) data and products from the Copernicus Programme current estimation methods still rarely integrate EO information to produce spatially explicit estimates. This paper reviews current methodologies for estimating ammonia in IIRs and in scientific literature, including advanced methods not yet implemented in official inventories but potentially capable of supporting more spatially explicit and process-oriented estimation. A Medium Effort Methodology (MEM) is identified among those reviewed as a representative methodological pathway for integrating EO information with Tier 3 approaches. Building on this, the paper explores the association between specific EO data and Copernicus products, and input variables required by MEM, identifying opportunities and barriers for environmental monitoring with potential relevance to sustainable agriculture. Full article

The successful realization of a circular economy in the cement industry, coupled with a substantial reduction in carbon emissions, relies on the development of sustainable alternative binder systems. This study investigated the physicomechanical performance and sulfate resistance of composites produced by alkali activation of natural perlite and blast furnace slag. The aim of the research was to improve mechanical properties under low- and medium-alkalinity conditions (5–10 M NaOH). The samples were cured at an ambient temperature of 20 °C and then treated with heat at 60 °C. These samples were then mechanically processed and subjected to five soak–dry cycles in 5% and 10% Na₂SO₄ solutions. The results showed that heat treatment resulted in the formation of a dense C-A-S-H gel, increasing compressive strength approximately eightfold, from 11.64 MPa to 92 MPa. However, perlite’s porous and brittle structure limits its flexural strength to 0.27 MPa; this value is insufficient for structural applications. Under severe sulfate attack (10% Na₂SO₄), samples cured at ambient temperature showed a 12% mass increase in the first cycle due to solution infiltration into capillary voids. As a consequence of extensive ettringite and gypsum formation, the specimens experienced severe deterioration, resulting in a complete loss of mechanical integrity and a residual compressive strength of 0 MPa. In contrast, heat-treated samples showed limited ion diffusion due to a denser matrix and an improved aggregate interface transition zone, resulting in a 2.6% mass increase and a residual compressive strength of 5.17 MPa. Consequently, the obtained findings indicate that thermally treated alkali-activated slag–perlite composites exhibit high resistance against sodium sulfate attack and may have potential for use in specific industrial environments with high sulfate concentrations. However, the performance of these materials under more complex aggressive conditions, such as mining environments involving magnesium sulfate exposure and acidic drainage waters, should be further validated through future studies. Full article

Industrial settlements of the East Kazakhstan Region face a persistent technogenic burden driven by the dense concentration of non-ferrous metallurgy and heat-and-power enterprises, further compounded by unfavorable pollutant dispersion conditions inherent to the region’s mountain–basin topography. This study evaluated spatiotemporal associations between annual mean concentrations of NO₂, SO₂, H₂S, and CO, the integrated air pollution index (API₅), and primary neoplasm morbidity across five settlements over the period 2014–2024. A retrospective ecological analysis was carried out for Ust-Kamenogorsk, Ridder, Altai, Shemonaikha, and the settlement of Glubokoe, incorporating Spearman’s rank correlation, lag analysis (1–3 years), and the Mann–Kendall trend test. Throughout the study period, neoplasm morbidity in the region consistently exceeded the national average by a factor of 1.3 to 2.0. In Ust-Kamenogorsk—where metallurgical SO₂ and NO₂ emissions are most heavily concentrated—strong positive associations were found in children for SO₂ (ρ = 0.791, p < 0.05) and in adolescents for NO₂ and CO, reflecting elevated inhalation exposure under conditions of chronic pollution. The negative associations with API₅ observed in Ridder and Altai, where the index showed a statistically significant downward trend, are interpreted as evidence of the inertial character of oncological processes and the lasting influence of cumulative past exposure. Across all studied settlements, SO₂ emerged as the most consistent predictor of morbidity variation. These findings support prioritizing stricter emission controls for SO₂ and NO₂ from metallurgical and energy facilities, establishing oncological screening programs for children and adolescents in chronically polluted areas, and strengthening ambient air monitoring—measures whose effective implementation will require coordinated action between public health authorities and environmental regulators. Full article

Greenhouse environments with restricted air exchange favor the accumulation of gaseous elemental mercury (GEM), posing potential exposure risks. However, the exact contribution of soil–air mercury fluxes to ambient greenhouse GEM, and the mechanisms by which organic manure application regulates this process, represent a critical knowledge gap. To address this, a 90-day simulated greenhouse incubation experiment (incorporating 0%, 1%, 2%, and 3% sheep manure fertilizer (SMF) amendments) and continuous 24 h micro-meteorological monitoring were conducted to evaluate GEM dynamics, soil Hg(0) fluxes, and mercury valence-state partitioning. Furthermore, macroscopic Hg(II) adsorption–desorption experiments were performed to elucidate the retention mechanisms. Our results demonstrated that while mechanical fertilization disturbances caused a transient short-term release of pre-existing Hg(0) on Day 0, both ambient GEM concentrations and soil Hg(0) emission fluxes generally declined over the long-term incubation period. Soil Hg(0) emission was identified as the predominant source process driving greenhouse GEM dynamics. Crucially, SMF addition consistently decreased operationally defined soil Hg(0) while relatively increasing the oxidized Hg(I) and Hg(II) fractions. Macroscopic batch experiments corroborated that SMF significantly enhanced Hg(II) retention and reduced its reactivation potential. Overall, under controlled experimental conditions, SMF exhibited a strong time-dependent suppressive effect on soil Hg(0) release and ambient GEM accumulation. These findings highlight the potential of organic manure in mitigating mercury risks in protected agriculture, though future molecular-level spectroscopic validations remain necessary to deduce the precise binding mechanisms. Full article

Reinforced concrete (RC) slabs, as the core load-bearing components in construction engineering, are prone to internal damage induced by impact loads, and accurate positioning of impact locations is a key task in structural health monitoring. The proposed method was developed for typical RC slabs such as building floors, bridge decks, and road slabs. Traditional acoustic emission (AE) positioning methods suffer from low positioning accuracy and a tendency to fall into local optimum when applied to RC slabs, which is attributed to the material’s heterogeneity, the complex propagation characteristics of stress waves and ambient noise interference. In this study, a GA-PSO hybrid algorithm is proposed, which integrates the global search capability of the Genetic Algorithm (GA) with the superior local convergence performance of the Particle Swarm Optimization (PSO) algorithm. The premature convergence issue of the traditional PSO algorithm is alleviated by adopting strategies including tournament selection, α hybrid crossover, boundary-constrained mutation, and linearly decreasing inertia weight. Based on the Time Difference of Arrival (TDOA) principle, the root mean square error between the theoretical and measured time differences is taken as the fitness function, and a boundary penalty mechanism is incorporated to ensure the physical validity of positioning results. AE data were acquired through drop weight impact tests to verify the performance of the proposed algorithm. Compared with traditional TDOA grid search, pure GA, and pure PSO methods under the same conditions, the proposed GA-PSO algorithm achieves an average localization error of only 54.95 mm, which is 61.0% lower than that of pure GA, while reducing the error standard deviation from approximately 114 mm to 24.87 mm. The average positioning error for all impact sources on the RC slab is within 100 mm, with the error in the central area as low as 42.97 mm. These results demonstrate that the GA-PSO algorithm significantly outperforms existing methods in terms of accuracy, stability, and maximum error control, verifying its high potential for impact source localization in complex heterogeneous materials. Full article

In light of the indispensable role of diesel engines in critical sectors such as heavy transportation, agricultural machinery, and shipping and the gradual depletion of fossil fuels, the strategic value of blended fuels has become increasingly prominent. However, the cold-start performance of diesel engines operating on blended fuels remains unclear. This study conducts a comprehensive simulation of the impact of various blended fuel ratios on the cold-start characteristics of diesel engines, focusing on low-temperature fluidity, combustion characteristics, and emissions. The research findings indicate that E30 and E50, as preferred blended fuels, exhibit excellent economic performance and environmental adaptability. Specifically, E30 demonstrates superior combustion performance and higher cylinder peak pressure under low-temperature conditions. In contrast, E50 shows a significant advantage in emissions performance, achieving 17.34% reductions in NOx and 9.7% in HC emissions compared to E30. In addition, a decrease in ambient temperature could help mitigate both NOx and HC emissions. Under simulated high-altitude conditions, E50 exhibits superior hypoxic adaptability compared to E30, achieving significant reductions in NOx (16.3%) and HC (9.7%). This study helps advance the development of clean alternative fuels for diesel engines by providing a theoretical foundation and practical guidelines for biodiesel selection across diverse environmental conditions. Full article

Unsaturated hydrocarbons, including alkenes, alkynes, and aromatic hydrocarbons, are important components of atmospheric volatile organic compounds (VOCs) and serve as key precursors for ozone, a major photochemical pollutant. This study aimed to characterize the sources and ozone formation potential of 29 unsaturated hydrocarbon VOCs in Beihai, a coastal city in southern China, on the basis of continuous online monitoring conducted during the summer of 2022. Continuous monitoring of unsaturated hydrocarbon VOCs in the ambient air of Beihai city during summer was conducted using a rapid online monitoring system for atmospheric VOCs. The results revealed that the total daily average concentration of unsaturated hydrocarbon VOCs was 1.21 ppbv, with an average concentration of 0.026 ppbv. The order of abundance was alkenes > aromatic hydrocarbons > alkynes. Source apportionment using the positive matrix factorization (PMF) model revealed that vehicle exhaust emissions were the primary source of unsaturated hydrocarbon VOCs in the city of Beihai, contributing 36.02%. Secondary sources included combustion sources (26.15%), solvent usage (18.55%), fuel evaporation (10.18%), and biogenic sources (9.10%). The contribution of unsaturated hydrocarbon VOCs to ozone formation was estimated using the ozone formation potential (OFP). Aromatic hydrocarbons contributed the most (51.22%), followed by alkenes (41.8%). Analysis of the diurnal variation patterns of unsaturated hydrocarbons revealed that combustion sources occurred during the night (01:00–02:00), suggesting that enhanced supervision and control measures during nighttime hours are warranted. Full article

Carbon nano-onions (CNOs) were synthesized at ambient conditions using the wick-pyrolysis technique with ghee as a precursor. A high-purity copper substrate produced unique CNOs, differing from those obtained with other metals. To purify the nanoparticles, they underwent treatment with a solvent mixture of acetone and deionized water or were pyrolyzed at 1000 °C under nitrogen without a catalyst. Various characterization techniques, including X-ray diffraction (XRD), Field Emission Scanning Electron Microscopy (FE-SEM), High-Resolution Transmission Electron Microscopy (HR-TEM), and Raman Spectroscopy, confirmed the successful formation of CNOs. Energy Dispersive Spectroscopy (EDS) and Elemental analysis (CHN) indicated the presence of oxygen in treated CNOs. X-ray photoelectron spectroscopy (XPS) revealed binding energies linked to C-O and C=O bonds. The average particle size was found to be 30–50 nm, with some agglomeration in pyrolyzed samples. A significant increase in surface area from 79.7 m²/g to 261.8 m²/g was observed, along with changes in pore radius and volume via Brunauer–Emmett–Teller (BET) analysis. Water contact angles on the CNO surface were measured at 125° and 138°, indicating hydrophobicity. Electrochemical tests on CNO-based composite electrodes yielded a specific capacitance of 109.7 F/g with 96% capacity retention over 5000 cycles. Full article

The aviation sector is under pressure to reduce greenhouse gas emissions. Proton exchange membrane fuel cell (PEMFC) systems are considered a promising option for sustainable aviation because of their high efficiency and suitability for electric propulsion. However, their performance deteriorates at high altitudes because reduced ambient pressure lowers the oxygen partial pressure at the cathode. This study investigated aviation PEMFC systems employing different air compression strategies under aircraft operating conditions. Three air supply configurations were examined: no compressor, a single-stage compressor, and a double-stage compressor. Among these, the double-stage configuration most effectively improved the reactant supply and stack output at high altitudes. Although the double-stage configuration increased compressor parasitic power consumption and required additional heat rejection through intercooling, its higher gross stack output compensated for these penalties and produced the highest net output. Achieving the same output with the no-compressor or single-stage compressor configuration would require additional cells and a larger stack. The system-specific power analysis showed that the double-stage configuration provided the most favorable mass-based performance. These results suggest that a double-stage-compressor configuration can be an effective air supply strategy for aviation PEMFC systems under high-altitude conditions. Full article

To address the issues of increased energy consumption and reduced engine efficiency in plug-in hybrid electric vehicles (PHEVs) under low-temperature conditions due to cabin heating demands, this paper investigates the coupling characteristics between the powertrain system and the cabin thermal management system and proposes an adaptive energy management strategy tailored for low-temperature environments. First, a comprehensive model incorporating vehicle dynamics, the engine, and the passenger compartment thermal management system was established. The impact of different ambient temperatures and equivalent factors on the system’s energy consumption characteristics was then quantitatively analyzed under WLTC conditions. Based on this, an adaptive strategy for minimizing equivalent fuel consumption that accounts for cabin heating demand was designed. By using real-time cabin heating demand and engine waste heat power as state feedback, the equivalent factor is dynamically adjusted to coordinate the allocation of power between propulsion and heating. Simulation and hardware-in-the-loop test results indicate that the optimized strategy, by promoting early engine engagement and improving waste heat recovery efficiency, reduces PTC energy consumption by 0.47 kWh under −20 °C WLTC conditions, decreases additional fuel consumption caused by low temperatures by approximately 59%, and improves the vehicle’s equivalent fuel economy by 4.6%, while effectively maintaining passenger compartment thermal comfort. This study contributes to sustainable transportation by reducing low-temperature-induced energy waste, lowering equivalent fuel consumption, and promoting efficient use of engine waste heat, thereby supporting carbon emission reduction goals in hybrid electric vehicle operations. Full article

Energy efficiency is a critical avenue for reducing carbonaceous emissions across fossil fuel value chains. Specifically, utilization of liquefied natural gas (LNG) exergy for power generation upon regasification in an import terminal offers the opportunity to partially retrieve the energy invested during liquefaction. Power generation arises as a promising avenue to accomplish this by using ambient air or seawater to supply heat to a working fluid, while the regasified LNG stream behaves as the heat sink of the thermal machine. However, a trade-off between cycle complexity (capital investment) and process efficiency exists. To identify it, in this work, three Rankine cycle configurations, which operate through indirect heat exchange without the need of fuel combustion, are analyzed with a consistent methodology from an exergo-economic perspective. Using a 2.13 mtpa LNG regasification terminal without LNG exergy utilization as the baseline for the techno-economic assessment, the simplest configuration consisting of a two-pressure level propane cycle (C₃) achieved an exergy efficiency of 34.0% and a levelized cost of electricity (LCOE) of 89.4 €/MWh. A cycle carrying out an expansion of a portion of the regasified LNG and employing a CO₂ loop for the high temperature range (C₁CO₂) achieved an exergy efficiency of 42.5% but with a higher LCOE of 99.7 €/MWh. Finally, the most capital-intensive design, comprising two stages with a hydrocarbon mixed refrigerant and propane as working fluids (MRC₃), reached an efficiency of 55.2% and a cost of electricity of 118.5 €/MWh. The exergy analysis revealed that minimizing the MITA of cryogenic exchangers should be prioritized to improve cycle performance. However, even when large LNG regasification capacities (>6 mtpa) are considered, the most cost-effective solution (C₃) generates profits during less than 45% of the time in the electricity market from 2024 of an LNG importing region such as Spain, indicating a relatively low economic potential for power generation without complementary heat sources. Full article

Assessing methane (CH₄) emissions is critical for mitigating the environmental impact of greenhouse gases (GHGs). Optical Gas Imaging (OGI) technologies have emerged as effective tools for gas leak detection and quantification; however, their performance under varying environmental conditions and gas compositions remains insufficiently understood. In particular, previous studies have largely overlooked the combined effects of ambient temperature variations and Carbone. Dioxide (CO₂) interference on both detection sensitivity and quantification accuracy. This study addresses this gap by systematically investigating the influence of temperature and CO₂ on methane detection and quantification using an infrared OGI camera coupled with real-time analysis software. Logistic regression was employed to model detection probability under two temperature conditions at a fixed distance of 45 m. Results show that at 30 °C, the system achieved 50% and 90% detection probabilities at 5.51 and 11.30 kg/h, respectively. In contrast, at −7 °C, detection reliability decreased due to increased false positives, preventing the establishment of robust detection thresholds. However, methane quantification accuracy improved under colder conditions, with 90% of leaks correctly quantified compared to 60% in warmer environments. Furthermore, the presence of CO₂ completely inhibited methane detection and quantification. These findings demonstrate the significant and previously underexplored impact of temperature and gas composition on OGI performance, highlighting critical limitations in real-world applications and providing new insights for improving methane monitoring strategies. Full article

Direct current (DC) surface flashover on polystyrene (PS) remains a critical bottleneck that impedes its reliable application in high-voltage insulation apparatus. To circumvent the protracted processing durations and stringent film-forming conditions inherent in conventional surface modification techniques, this study proposes a novel “liquid-film-assisted in situ rapid plasma curing” strategy. By harnessing atmospheric-pressure dielectric barrier discharge (DBD) technology within an argon ambient, the rapid (<6 min) and efficient deposition of a fluorosilane (FAS-13) functional coating onto the substrate was achieved. Microscopic characterizations coupled with isothermal surface potential decay (SPD) measurements reveal that this coating substantially mitigates the detrapping and surface migration of charge carriers. Macroscopic DC flashover testing corroborates that, under the optimal modification ratio, the surface breakdown voltage of PS is elevated to 14.04 kV, yielding an insulation gain of 26.94%. To elucidate the underlying physical mechanisms, density functional theory (DFT) calculations were conducted, revealing that the energy band misalignment between the wide-bandgap fluorinated layer and the substrate facilitates the construction of a high-density deep trap network (with a depth of ~0.8 eV) at the coating–substrate interface. By robustly anchoring primary electrons and inducing the formation of a homopolar space charge shielding layer, these deep traps physically arrest the evolution of the secondary electron emission avalanche (SEEA). Consequently, this work not only establishes a viable engineering framework for the rapid, large-scale surface reinforcement of DC insulation equipment but also provides profound quantum chemical insights into interfacial trap regulation within all-organic dielectrics. Full article